/*
 * Copyright (C) 2022 panpf <panpfpanpf@outlook.com>
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.github.panpf.sketch.transition

import androidx.annotation.MainThread
import com.github.panpf.sketch.request.DisplayResult
import com.github.panpf.sketch.target.Target

/**
 * A class to animate between a [Target]'s current drawable and the result of an image request.
 *
 * NOTE: A [Target] must implement [TransitionDisplayTarget] to support applying [Transition]s.
 * If the [Target] does not implement [TransitionDisplayTarget], any [Transition]s will be ignored.
 */
fun interface Transition {

    /**
     * Start the transition animation.
     *
     * Implementations are responsible for calling the correct [Target] lifecycle callback.
     * See [CrossfadeTransition] for an example.
     */
    @MainThread
    fun transition()

    fun interface Factory {

        fun create(
            target: TransitionDisplayTarget,
            result: DisplayResult,
            fitScale: Boolean
        ): Transition?
    }
}